Twine and method of manufacture thereof



April 19, 1955 G. SLAYTER TWINE AND METHOD OF MANUFACTURE Tl-KEREOF Filed April 28, 1951 United States Patent TWINE AND METHOD OF MANUFACTURE THEREOF Games Slayter, Newark, Ohio, assignor to Owens-Corning Fiberglas Corporation, a corporation of Delaware Application April 28, 1951, Serial No. 223,457

3 Claims. c1. 57-140 This invention relates to the production of strong, tough twines such as baler or binder twines and to a particular twine and a method for its manufacture.

Tough twines such as those used in balers and binders usually are made of relatively long, tough fibrous material such as sisal and hemp and the like. Most baler and binder twine is, in fact, made from sisal fibers which average approximately forty inches in length and which are staggered and orientated longitudinally and then twisted to form twine.

The production of sisal fibers requires certain conditions of temperature and humidity found for the most part in tropical and semi-tropical countries and, consequently, almost all sisal fiber used in the United States must be imported from those lands where it is raised. The upheavals of economic conditions throughout the world have rendered the supply of sisal fiber perilous and have increased its cost to such an extent that substitutes for such fiber in whole, or at least in part, must be found in order to permit the continuance of the use of sisal at all in baler and binder twines.

Substitute fibers, however, be they natural or artificial,

preferably should be of such nature as to replace natural fibers in whole or in part in the fabrication of twines which still can be handled in the tens of thousands of baling, binding and tying machines specifically designed for and capable of handling natural fiber twines. If the substitute or improved materials were to be too greatly different in their characteristics from the natural fibers, these thousands of machines would be rendered obsolete. Thus, any substitute or improved fiber which is proposed for use either in place of or in connection with natural fiber, must possess qualities which should preferably be even superior to those of the natural fiber and yet a twine fabricated from such fiber must be usable in machines designed for handling natural fiber twines. It is an object of this invention to provide a method for the fabrication of a novel twine in which a substitute fiber is used in place of at least a part of the natural fiber formerly used in such a twine.

It is another object of this invention to provide a method by which glass fiber strands can be introduced into and with sisal fibers in the fabrication of baler and binder twines having substantially the same characteristics as all natural fiber twines.

It is yet another object of this invention to provide a novel baler or binder twine having substantially all of the qualities and characteristics of twine made of natural fibers such as sisal and having certain improved qualities.

These objects and more specific objects and advantages will become apparent from the description which follows and from the drawings, in which:

Fig. 1 is a simplified, somewhat diagrammatic illustration of mechanism on which the method of the instant invention may be carried out for the production of a twine embodying the invention.

Fig. 2 is a greatly enlarged transverse sectional view of an illustrative twine embodying the invention.

Figure 3 is a view similar to Figure 1 showing a portion of the mechanism and illustrating a modification.

A generally conventional twine making machine is somewhat diagrammatically illustrated in Fig. l of the drawings and may comprise, among numerous other parts not shown therein, a plurality of feeding belts 10, 11 and 12, of which only three are illustrated, that carry randomly distributed fibers from bulk fiber sources. In

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Fig. 1 the machine is shown as having two such feeding belts 10 and 11, and one feeding belt 12 for feeding masses of natural fibers 13 and 14 and glass fibers 15 respectively.

The glass fibers 15 which are carried into the machine by the feeding belt 12 may be produced in a manner well known in the art by high speed drawing from heated orifices and after cooling and collection of the fibers into strands, the strands may be cut to approximately forty inch lengths so that they can be handled by machinery already in existence for the handling of sisal fibers, for example, which average approximately forty inches in length. If glass fiber strands are to be used in combination with other fibers, either natural or artificial, they should be cut in lengths generally corresponding to the other fibers. During the production of the glass fiber strands which are carried by the belt 12, each of the approximately two hundred fibers in each strand is coated with a suitable hardenable synthetic resin, for example a thermosetting resin such as phenol formaldehyde, and the resin is polymerized to form a stiffening coating on the fibers and bind the fibers together in the strand. This makes the fibers and the strands wiry and tough, reducing their flexibility and approximating natural sisal fibers with which the glass fibers are to be interworked. Other resins having similar characteristics of adhesion to glass and which set up into hard relatively inflexible layers may satisfactorily be used, such as urea formaldehyde, melamine formaldehyde, polyester resins, for example, pentaerythritol fumarate, and others.

Suitable glass fiber strands pretreated in such a manner are carried by the belt 12 in a manner similar to that in which the belts 1t) and 11 carry the natural fibers and deposited in successive layers on a travelling conveyor belt 16 which moves horizontally beneath the lower ends of the belts 10, 11 and 12. The belt 16 may be fabricated, for example, from a multiple number of horizontally adjacent strands of bicycle chain. It runs at the linear speed required to keep pace with rapid efiicient twisting and balling of the sliver of fibrous material produced by the belt. The belt 16 is provided with a multiplicity of upwardly extending pointed fingers 17 which serve to pull the fibers from the belts 11, 12 and 13 and to commence their orientation into general parallelism over the surface of the bicycle chains making up the belt 16.

A machine of this type, which is generally referred to as a pin drafter, frequently has auxiliary fingers 18 mounted upon racks 19. The racks 19 are reciprocated up and through the fibers; then moved horizontally through the fibers; then down and out of the fibers and back beneath the belt 16. The horizontal forward move- 'ment of the pins 18 (to the right in Fig. 1) takes place at a linear speed greater than the linear speed of the moving belt 16 and this action tends to comb or draft the fibers gradually reducing the thickness of the layer of fibers on the belt 16 and orienting them into generally lon itudinally parallel and staggered relationship.

The drafting machine may also be equipped with one or more rotary drafting wheels 20, the peripheries of which are studded with drafting pins 21 that are bent backwardly relative to the direction of rotation of the wheels. The wheels 20 are rotated at a linear speed in excess of the linear speed of travel of the belt 16, similarly to orientate the fibers thereon. A drafting machine may be equipped with either of these faster moving elements, i. e., the linear moving pins 18 or rotary pins 21, or both, or with similar structures, the purpose of them all being to orientate the fibrous layer into a uniform layer of fibers on the belt 17, to intermix them, at least to a considerable extent and to reduce the thickness of the fibrous layer to that required for the twine to be twisted.

As the fibers progress along the belt 16 they gradually become more tightly compacted by virtue of the combing or drafting and finally are led between compacting roll ers 22 which have concave grooved peripheries for the purpose of forming the fibers into a bundle of generally circular cross section.

Shown in Fig. 2 is a second manner of introducing the glass fiber strands into the natural fibers. In this second method, balls of continuous glass fiber strands are positioned near the machine, as shown by the sample ball 23. Each ball may carry or more strands Wound as a unit and led from the ball together over idler rollers 24 and 25 into the rollers 22 with the orientated natural fibers. The number of balls and the number of strands on each depends, of course, on the total amount of glass to be added. Depending upon the tension on the glass fiber strands fed from. the balls 23, the glass fibers may be orientated towards the center of the mass of fibers grouped together by the rollers 22 or they may be allowed to disperse in random manner through such mass of fibers. The tension on the glass fiber strands retains them in longitudinal relationship with respect to the natural fibers. 1f the tension on the glass strands is high, the natural fibers are twisted around the glass in the subsequent operations and if the tension on the glass strands is lower, the glass strands are twisted with the natural fibers, not being nearly so concentrated at the center, into random locations in the twine.

Whether the glass fiber strands are introduced in short lengths prior to drafting and compacting (Fig. 1) or whether they are introduced from a supply of continuous length strands (Fig. 3) at the compacting stage, treatment of the intermixed fibers subsequent to compacting by the rollers 22 is substantially identical.

The generally grouped sliver or roving 26 which leaves the rollers 22, passes through a somewhat cone shaped orifice 27 in a twisting machine and thence over an eye 28 on a revoluble arm 29 which is revolved around a reciprocating, rotating spindle 30. The spindle 30 is reciprocated at a speed proper to take up the twine being produced and to accept the twine being wrapped thereon by the fiyer arm 29 in helical turns. The timing of the reciprocation and rotation of the spindle 30 with the rotation of the flyer 29 is selected to produce in the twine, between the exit end of the orifice 27 and the eye 28 of the fiyer 29, a twist of a selected number of turns per inch or other linear measurement.

Fig. 2 illustrates in greatly enlarged scale a cross sectional view of a twine embodying the invention. The broken line in Fig. 2 is the outline of the surface of the twine. Natural fibers are shown in solid lines and are illustrated as having generally rectangular cross sections. Strands of glass fibers are shown as consisting of a relatively few fibers of generally circular cross section. Be cause of the very small diameter of the individual fibers in the glass strands it is impossible to correctly show the relative sizes of each individual natural fiber as contrasted to the individual glass fibers. However, from the showing in Fig. 2, it can be seen that the glass fibers are rather generally distributed throughout the twine (unless they are fed in continuous form with substantial tension) and are usually surrounded by natural fibers through which they are interspersed. Because of the tremendously high tensile strength of glass, in the order of 400,000 pounds per square inch, the presence of even a relatively small percentage of glass in a twine contributes greatly to its tensile strength, increasing it much more percentagewise than the per cent of glass present in the sisal, for example, on a weight basis. The presence of the natural fibers in combination with the glass helps protect the individual glass figers from each other and reduces the abrasive efiect of the glass fibers on each other thus eliminating one of the frequently expressed poor characteristics of glass when used in filamentary material. The high resiliency of glass allows it to be flexed along with, and as easily as the natural fibers. The presence of a substantial proportion of glass fibers in a twine of this nature thus improves the characteristics of the twine over the similar characteristics of an all natural fiber twine. For example, in tests made of twine containing 10 per cent by weight of glass and 90 per cent by weight of sisal, the knot strength of the twine was increased from approximately 144 pounds for an all sisal twine of the same size to 165 pounds.

Inasmuch as glass fibers are synthetic materials and are produced from natural substances readily available in many parts of the world and in varying temperatures and climates, their supply is not dependent upon conditions which restrict the availability in diflicult political times. The production of many hundreds of thousands of pounds of twine per year as required is facilitated and dependence upon imported material reduced to any extent to which it is desired the glass fibers may be used.

The maximum percentage of glass fibers to natural fibers in such a combination twine is dictated by the meeting place of two opposite characteristics. The first desirable characteristic of a baler or hinder twine is that it shall have approximately the same size when finished as that of a natural twine of the same strength so that it can be handled in tying and knotting equipment already in existence. Conversely, a twine must have certain minimum tensile and knot strengths in order successfully to perform the functions of baling and binding materials. For example, twine designed for the baling of hay must have a minimum knot strength of approximately to pounds to permit the hay to be held in tightly compressed and baled condition. While the increase in proportion by weight of glass fibers might be expected to increase the tensile and knot strengths of the twine carrying such substitution to its ultimate and replacing the natural fibers entirely by glass introduces other problems. When a twine is pulled through a relatively tight bend as in knotting, a 100 per cent glass fiber twine must be especially fabricated and handled in order to give satisfactory knot strengths. By combining the glass fiber strands with natural fibers special pretreatment of the glass fibers to an extent necessary in all glass fiber twines is eliminated and thus the final accumulation of the fibers for the twisting of the twine is simplified and rendered less costly.

I claim:

1. A method for the reinforcement of sisal fiber twine that includes the steps of coating continuous glass fiber strands with a hardenable synthetic resin, setting the resin, cutting the coated strands into lengths approximating that of the sisal fibers, and introducing the cut coated glass fibers in a random manner into a selected mass of sisal fibers before drafting and twisting.

2. A tough twine comprising an admixture consisting of a major portion by weight of discontinuous longitudinaly orientated sisal fibers twisted together with a minor portion by weight of discontinuous glass fiber strands longitudinally orientated with and interspersed in the sisal fibers, each of said strands being composed of a multiplicity of glass fibers arranged side by side in compact relation and adhered together by a coating material.

3. A tough twine consisting in an admixture of a major portion by weight of discontinuous longitudinally orientated sisal fibers twisted together with a minor portion by weight of discontinuous resin coated glass fiber strands longitudinally orientated with and interspersed in random arrangement in the sisal fibers, each of said strands being composed of a multiplicity of glass fibers arranged side by side in compact relation.

OTHER REFERENCES 12gThe New Fibers, 1946, Sherman and Sherman; page 

